1. Field of the Invention
The present invention concerns a conveying system suitable for conveying blood samples, including at least one tube connection with an internal cross-dimension/diameter/diagonal, at least one dispatch station and at least one receiver station, where items are conveyed by airflow in the direction of the airflow in the tube connection from a dispatch station to a receiver station. The invention also concerns the use of such a conveying system.
2. Description of Related Art
It is commonly known to use conveying systems with a number of tube connections wherein items are sent from a dispatch station to a receiver station by means of vacuum or pressurised air. Typically, an elongated capsule is sent which is provided with sealing rings at each end so that the cross-section of the tube connection is filled in this way. The capsule thereby acts as a plug which is conveyed in a long tube system. In the capsule there is typically provided the item to be transported to the desired destination. Such systems are known as so-called pneumatic dispatch systems and have been used for a long time in connection with internal post or similar in large buildings. However, by such systems there is the inexpediency that several items cannot be sent in immediate succession just like that. This is due to the fact that the systems are closed systems and that the capsule will stop underway in the tube connection if the closed system receives “false air”. In order to be able to send capsules as quickly as possible in succession, various systems have been developed. One system may be provided with an indicator showing when a capsule is at the end station and thereby that the system is ready for use again. There are also other variants of pneumatic dispatch systems that are divided into different sections where each section is provided with its own vacuum or blowing mechanism. This allows for a new capsule to be sent as soon as the previously sent capsule has passed given positions in the tube connection.
However, such solutions all depend on the item to be conveyed to be put into a capsule and then to be dispatched. Also, it is necessary to take the item out of the capsule at the other end of the system. If approximately the same amount of capsules are sent both ways, the problem of an accumulated amount of capsules at a receiver station and a lacking amount of capsules at a dispatch station is solved, but in very few cases there will be a need for receiving capsules at respective dispatch stations, something which is not expedient. Such a system is known from U.S. Pat. No. 7,424,340 B2.
From FR 2 639 336 is known a solution where coins are conveyed in a tube connection with a cross-section greater than that of the coins. This kind of tube conveying system is possibly suited for some types of items, e.g. coins, by which a more or less chaotic transport of the items is allowable. In FR 2 639 336 it appears that coins are put in and conveyed without any further precautions, why such a system is not suited for conveying items where a certain control and guiding of the sent items is supposed and where they are to be received in a given order.
From U.S. Pat. No. 2,890,913 a system for conveying items such as vials is known. This system allows only one item to be in the system, as the system comprises a kind of turning point, where the item via a trap door is stopped and then by help of gravity falls into a receiving station. As this system only allows for one item to be in the system during a period of time, there is a need for having a signal for when it is possible to send the next item. Further the items are accelerated by a “shot” of pressurized air, and the item will be subject to quite a shock and a rough handling, as it is hit by the air. Such a system is troublesome due to the fact that it can only handle one item at a time and does not fulfil requirements to such a system nowadays.
From U.S. Pat. No. 3,945,682 another system is know, where more items can be conveyed together and successively. However this system concerns an opening where items are sucked in and send via a channel to a further process, where the items are turned end on end and resend. To help the sending of the items pressurized air can be used to move the items into the suction channel. There is used an airflow from two different sources and no constant airflow is provided. The part of the airflow from the suction is continuous, but as two different sources for providing the airflows are used, the items will experience a pulsating movement, which can have a negative influence on items that has to be transported without too much disturbance and jolting.
Further a system as seen in U.S. Pat. No. 3,945,682 will only work for moving items a relatively short distance as the continuous airflow that provides the suction and at the same time is the carrying medium for the items always will flow the way with the least resistance in the system of channels. When the channel system has a certain length and thus a corresponding friction and resistance the flow of air will only be in the wanted direction as long as there is no other way with less friction and resistance. This fact and the problem of such a system arises due to the system being an open system, where the continuous airflow is supplied to the channel system at a distance to the dispatch station, and sucking in ambient air at the dispatch station due to the common known ejector principle also known as the venturi effect. If a channel system of such a conveying system has a certain length or a certain numbers of items to convey the flow of air will turn and air will be pressed out of the dispatch station contrary to the intention with the system.